The present invention is directed to devices utilizing radar. In particular, the present invention is directed to low power radar devices and to radar-controlled fluid flow control devices and bathroom, restroom, or kitchen fixtures.
In light of concerns about public health and safety, the development of touchless controls on bathroom and restroom fixtures has received a large amount of attention. Germs, bacteria, disease, and other harmful materials may be spread from one person to another by touching the handles on toilets, urinals, sinks, and other fixtures in public restrooms.
A variety of touchless control systems have been developed. Many conventional touchless control systems employ an infrared or, less commonly, a visible light detector for sensing a user. The detector typically produces appropriate signals that open or close an actuator, such as a valve, attached to a water inlet conduit of the fixture to, for example, flush a toilet or cause a stream of water to flow out of a faucet. Infrared radiation can be detected passively by sensing heat from a user. Alternatively, infrared light can be emitted by a device, such as a light emitting diode (LED), and reflected from a user to an infrared detector, such as a photocell.
The use of infrared detection has several limitations. First, infrared radiation cannot penetrate most materials because of the short wavelength of the radiation. Thus, infrared emitters and detectors are typically either exposed or are positioned behind a window made of material that is transparent to infrared radiation. In addition, infrared sensors can be inadvertently or purposefully blocked by the presence of material, such as paper, dust, or cloth, in front of the emitter or detector.
Another disadvantage of infrared detection is that the reflectivity of objects, such as clothing, varies widely. Thus, the infrared detector must be sensitive to a wide variation in the strength of reflected signals. There is a risk that the detector may fail to detect a user with clothing or other articles that absorb or only weakly reflect infrared radiation.
These disadvantages of infrared detectors may cause faulty responses by the fixture (e.g., flushing of a toilet at an inappropriate time or maintaining constant flow of water in a toilet or sink) or may result in a failure to operate until the sensor area is cleaned or blocking objects are removed. Thus, there is a need for a new type of detector that can overcome these deficiencies of current detectors.
Another issue is the amount of power available for operating automatic or touchless fixtures. These devices may be battery-operated for convenience or because there is no near source of ac power. To operate for a year or more, it is often necessary to prepare low power devices. Many types of detection devices require significant amounts of power and new ways need to be developed to reduce the power needs of such devices.
The present invention is directed to fluid flow devices and sensors that may address these needs. In one embodiment, a fluid flow device includes an actuator, an RF transmitter, a gated RF receiver, and a processor. The RF transmitter is configured and arranged to produce a plurality of pulses of RF energy spaced apart in time to form a sensor field. The gated RF receiver is configured and arranged to receive RF energy reflected by objects within the sensor field. The processor is coupled to the gated RF receiver for evaluating the reflected RF energy. The processor is also coupled to the actuator and is configured and arranged to activate the actuator in response to the reflected RF energy to control fluid flow.
Another embodiment is a fixture that includes a valve for controlling fluid flow through the fixture, an actuator for opening and closing the valve, and a sensor for activating the actuator. The sensor includes an RF transmitter, a gated RF receiver, and a processor. The RF transmitter is configured and arranged to produce a plurality of pulses of RF energy spaced apart in time to form a sensor field. The gated RF receiver is configured and arranged to receive RF energy reflected by objects within the sensor field. The processor is coupled to the gated RF receiver for evaluating the reflected RF energy. The processor is also coupled to the actuator and is configured and arranged to activate the actuator in response to the reflected RF energy to control fluid flow.
Another embodiment is a method of providing fluid flow in response to a user. A pulsed RF signal is transmitted by a transmitter to form a sensor field. Reflections of the RF signal are received by a receiver from objects within the sensor field. These reflections are evaluated to determine a characteristic of a user. An actuator is activated based on the evaluation of the reflections of the RF signal. The actuator controls fluid flow in a fixture.
Yet another embodiment is a sensor. The sensor includes a burst initiator, a transmitter pulse generator, an RF oscillator, a transmitter antenna, a receiver antenna, a receiver pulse generator, a receiver delay line, and a receiver sampler. The burst initiator provides a plurality of bursts at a burst rate and having a burst width that is 5% or less than a time between bursts. The transmitter pulse generator produces a plurality of transmitter pulses at a transmitter pulse rate and with a transmitter pulse width during each burst. The RF oscillator provides pulses of RF energy in response to the transmitter pulses and the transmitter antenna transmits the pulses of RF energy to form a sensor field. The receiver antenna receives RF energy reflected off objects in the sensor field. The receiver pulse generator is couple to the transmitter pulse generator and generates receiver pulses at a receiver pulse rate and with receiver pulse width. The receiver delay line delays the receiver pulses with respect to the transmitter pulses. The receiver sampler samples the RF energy receiver by the receiver antenna during the receiver pulses.